Lewis Hamilton's says his decision to use an old-specification rear wing cost him a shot at pole position during qualifying for the Belgian Grand Prix after team-mate Jenson Button finished on top with a new design.

Hamilton used the new, lower-drag wing in final practice but could not find a decent balance during the hour-long session and opted to change back to a higher downforce setting. After qualifying seventh on the grid he admitted the decision had been a mistake.

"For me, today was a bit of a disappointment; but, since I'm still in the top 10, tomorrow will be about trying to make the most of things," he said. "The set-up wasn't perfect, but that was simply because we chose the wrong rear wing, preferring to stay with the version we used in Hungary.

"The wing we'd been using in FP3 this morning hadn't been working very well, so we opted to go back to the older wing which we thought would be the safer option. It was a collective choice: we thought the older wing would be quicker in qualifying, but in fact Jenson has shown the new wing to be very good indeed. Our side of the garage was a bit unlucky, but we'll do what we can with what we have tomorrow."

Hamilton also tweeted that he was hoping McLaren could pull off a one-two on Sunday.

"Congrats to Jenson Button for his first pole for the team," he wrote. "I will try to help him score a 1-2 for the team. Still all to play for."